Question

Dalton’s law of partial pressure is not applicable to:
(A)- ${{O}_{2}}+{{O}_{3}}$
(B)- $CO+C{{O}_{2}}$
(C)- $N{{H}_{3}}+HCl$
(D)- ${{I}_{2}}+{{O}_{2}}$

Answer 1

The law will help to identify the gaseous mixtures which do interact amongst themselves and thus obey the law. There is thus, an absence of chemical reaction in the mixture.

Complete step by step answer:
Dalton's law of partial pressure states that the total partial pressure over the mixture is equal to the sum of the partial pressures by the individual gas molecules present in it, So that the gas particles do not react with each other, involving only the elastic collision within it, that is, the ideal gases. Thus, the law is applicable to the ideal gases.
In the real gases, due to the presence of interaction between the gasses like attraction or repulsion. It does not purely give the pressure with respect to the pure gas. Thus, showing slight deviation from the law.
For the given system, to which the law is applicable is determined by unavailability of the reaction between the substances.
In case of ${{O}_{2}}+{{O}_{3}}$ , $CO+C{{O}_{2}}$ and ${{I}_{2}}+{{O}_{2}}$, both the substances are non-reacting and thus, no occurrence of reaction. Therefore, obey Dalton's law.
Whereas, in case of $N{{H}_{3}}+HCl$, both the gaseous substances undergo complex reactions to form solid ammonium chloride products, giving neutralization reaction. As both the gases react, it does not obey the law.
So, the correct answer is “Option C”.

Note: As discussed above, the real gases show variation form the law. But at low temperatures and pressure, the real gases behave like ideal gases. So, the law is applicable to the real gases at extreme low temperature and pressure.